Clear completion marker upon resetting slot switch

Test: tested compilation

Bug: 254628935
Change-Id: Idc978271efb4950f78f45772063e8506e9888553
diff --git a/aosp/update_attempter_android.cc b/aosp/update_attempter_android.cc
index 1243a7f..0dc7f83 100644
--- a/aosp/update_attempter_android.cc
+++ b/aosp/update_attempter_android.cc
@@ -1229,6 +1229,7 @@
     return LogAndSetError(
         error, FROM_HERE, "Already processing an update, cancel it first.");
   }
+  TEST_AND_RETURN_FALSE(ClearUpdateCompletedMarker());
   // Update the boot flags so the current slot has higher priority.
   if (!boot_control_->SetActiveBootSlot(GetCurrentSlot())) {
     return LogAndSetError(error, FROM_HERE, "Failed to SetActiveBootSlot");